<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0 auto;
        }

        .father {
            width: 400px;
            height: 400px;
            background-color: yellow;
        }

        .son {
            width: 100px;
            height: 100px;
            background-color: green;
            display: block;
        }
    </style>
    <script src="./js/ex004mouseenter和mousemove区别.js"></script>
</head>
<body>
    <div class="father">
        我是父亲
        <a class="son">我是儿子</a>
    </div>
</body>
</html>